How to Improve Offshore Turbines

Written By Brianna Panzica

Posted August 21, 2012

The wind power industry is growing all over the world.

In 2010, the EIA reported that it was the fastest-growing new energy generation method in the U.S., accounting for 2.3% of energy production. The U.S. currently accounts for 28% of the world’s wind power, more than any other nation.

But as far as total production goes, the U.S. lags behind. Denmark, home of leading turbine maker Vestas Wind Systems (CPH: VWS), received 20% of its total power from wind in 2009.

The UK has fifteen offshore wind farms currently operating, with more planned and under construction and a goal of 17% electricity from offshore sources by 2020.

The U.S. currently has no offshore wind farms, though just this week its first planned offshore farm, Cape Wind, received approval.

Offshore wind power is growing, and rightly so. Onshore farms can’t expand forever – they take up too much valuable land. But offshore turbines don’t interfere with neighborhoods, agriculture, or industrial expansion.

They are, however, more expensive than onshore farms. The turbines require more support to stand in the water, and they’re more difficult to situate.

Ideal offshore turbines would be made at a reduced cost and would have improved efficiency. And engineer Jim Platts of the University of Cambridge’s Institute for Manufacturing (IfM) has determined how this can be done.

Platts has a pretty decent track record. He developed a turbine designs and a team in the ’80s that accounted for all the wind turbines in the UK. His team developed into the Global Blade Technology division of Vestas.

And now he has conducted a study with IfM resulting in suggestions for improvements in the offshore turbine industry at large.

The main problem, the study notes, is the high amount and high cost of materials in offshore turbines.

Turbine efficiency is measured by harvesting ratio, which is the energy provided by the turbine compared to the energy required to manufacture it.

Onshore turbines have a harvesting ratio of 40:1. For offshore, meanwhile, this is closer to 15:1.

And the main difference is in construction. The blades, gearbox, and generator mechanism are roughly the same for both. But offshore turbines have much larger foundations (located below the water, so we don’t generally see them) and heavier and taller turbines.

In short, this means more steel and concrete.

But Platts offers several solutions – solutions that could double offshore harvesting ratios.

His preliminary solution is guyed towers. Turbines would be supported by steel cables anchored into the ocean floor. With this kind of support, neither the tower nor the foundation would need to be so large.

The amount of steel and concrete that would be trimmed off the tower and foundation with the use of guyed towers alone would be enough to increase the harvesting ratio to 25:1, the IfM study reports.

But that’s not all that could be done. Another problem the turbines face is the steel itself.

Platts explains:

“Steel is prone to corrosion and fatigue. This begs the question: could we do better with other materials. The answer is yes, we can use composites for towers just as we do for blades. They are lighter, stronger, corrosion free and more resilient than steel.”

Turbine blades are already made out of composite materials, so it wouldn’t be that far off to imagine the turbine manufacturers using the same things for the towers. Again, Platts describes how easy this could be:

“It’s often overlooked that manufacturers of turbines have driven advances in composites, producing materials with 95 per cent of the performance of the high-cost composites made for the aeronautical sector at 5 per cent of the cost. Much of this work has been led by UK companies. These companies now need to look at new ways of working.”

Switching to composites, he says, would further increase the harvesting ratio of these turbines to 32:1 – putting them pretty close to onshore turbines. And because they hold up much better to corrosion (which we can imagine would be a pretty big factor in the ocean), the materials could extend turbine life to 60 years from its current lifetime of 20 years.

If companies manufacturing offshore turbines were to adopt the measures Platts suggests, the turbines would be able to offer a lot more to the energy industry. At the lower costs, they’d likely become more abundant.

Wind power could be the next big wave in the energy industry. In the past twenty years, world capacity has shot up over 250 billion kilowatt-hours from almost nothing.

And as technology and innovation, like Platts’ careful consideration, continue to make it more affordable and more efficient, it could begin to take over.

That’s all for now,

Brianna Panzica

follow basic@brianna_panzica on Twitter

Energy & Capital’s modern energy guru, Brianna digs deep into the industry with accurate and insightful updates into the biggest energy companies and events. She stays up to date with the latest market moves and industry finds, bringing readers a unique view of current energy trends.

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